Fuel pump for internal-combustion engines



Nov. 20, 1945.

w. w. LOWTHER 2,389,159

FUEL PUMP FOR INTERNAL-COMBUSTION ENGINES Filed Aug. 18, 1941 :1 l Q b 5, 1 I 21:: 5- 1 s :17 24 2- I18 1 6 Z r o g '40 J 1V2 tie f 5 Z 14 i3 14 27 12 M. 9, g 39 25 Z 4 D 5i v 2-\ 2s 1570622 iofi Wifred WZOWIVMI pumping device.

Patented Nov. 20, 19 45 umrao .STATES" PATENT OFFICE war. rum ron gtizan-comusnon wmreow. Lowther, Minneapolis, Minn.

Application August-18, 1941, Serial No. 401,321

2 Claims. (01'. 123-139);

My present invention relates to an improved system for feeding fuel to internal combustion More specifically stated, my present invention may be said to relate to improvements in fuel feeding systems of the general character wherein the pulsating pressure produced in the cylinder oi an internal combustion engine is employed as a source of motivating energy for actuating a Heretofore, numerous fuel pumping systems utilizing the varying or pulsating pressure inthe cylinder of an internal combustion engine as a source of motivating energy have been proposed,

but all these prior art systems have been found objectionable and have failed to meet commercial requirements; Among the most serious objections to prior art devices of this general character was the transmission of such excessively high temperatures from the associated engine cylinder to the pumping device and extending fuel conduits as to cause one or more of the following troubles, to wit: (a) premature breakdown of the pumping mechanism itself, or of its pressure control valve mechanism in cases where the latter were employed: and (b) the heating of liquid fuel to excessive temperatures at critical points in the system, caus'mg inoperativenes of the pumping system due to vapor lock, trouble of this kind being particularly prevalent in ensines using highly volatile iuei such as gasoline.

An important objective of the present invention open and establish communication between the engine cylinder andpumping device for intervals of engine operation between power delivery periods and during which intervals the pressures and temperatures in the cylinder and its combustion chamberare relatively very low as compared to 1 the pressures and temperatures resulting from is the provision oi an improved liquid fuel feeding system of the kind described in which the heat transfer to the pumping device from the engine cylinder is reduced to a u u and, in fact. is so low as to cause no serious or objectionable rise in temperature in the pumping device proper or the fuel contained therein or within its extending fuel conduits. To this end I have incorporated, in-the preferred embodiment oi the invention herein illustrated, the following ance with my present invention an automatic pressure operated valve controls communication between the engine cylinder and the pumping de vice and this valve is balanced to automatically 65 The above and-other highly important objeccombustion and present during the power delivery period, and said valve is balanced to close and automatically disrupted during the explosion periods and power delivery strokes or movements of the piston, at which times the pressures and temperatures are very high in the cylinder and its combustion chamber. I

(b) As another important feature of the preferred embodiment of the invention, I locate the seat of the pressure operated valve within a cooled wall of the engine cylinder so that communication between the engine cylinder and the pumping de-' vice operated from the pulsating pressure produced in the engine cylinder is disrupted or broken off during high pressure periods, substantially at the point of opening of the pressure conduit into the engine cylinder, whereby high pressure, high temperature gases that are present in the engine cylinder and combustion chamber portion of the cylinder during the power strokes or movements of the piston thereof are prevented from entering any portion of the connecting pressure conduit outwardly of the engine cylinder or cornbustion chamber wall. This is considered a highly important step forward in the art in that it provents high temperature gases present in the combustion chamber during the power strokes or movements .of the cylinder piston from entering and thereby heating up any portion of the conduit outwardly of the cooled wall of the cylinder or its combustion chamber to a temperature above the temperature of the cooled cylinder or combustion chamber walls; and, in this connection, it may be stated that the location of this pressure cut-oil valve at any point in the pressure conduit outwardly of the combustion chamber or cylin- .der cooled wall will result in heating up of the pressure conduit at the engine side of the valve to temperatures far above that of the cooled walls of the cylinder and combustion chamber and that this heat will be'conducted past the valve and through the opposite side of the pressure conduit to the pumping device through the conduit and present invention is the provision of an improved pressure control valve for the purpose specified.

tives and advantages of the invention will be made apparent from'the following specification and claims and the accompanying drawing.

In the single view of the drawing, which illustrates a preferred embodiment of the invention, like characters indicate like parts. With reference to the drawing the single view thereof is'a view in axial section, with some parts broken away and some parts shown in full, of a complete fuel pumping apparatus operatively connected to a piston-equipped cylinder of an internal combustion engine.

The internal combustion engine, only a fragmentary portion of one piston-equipped cylinder of which is illustrated, is indicated as an entirety by the numeral 2 and may, for the purpose of the present example, be assumed to be of the four cycle, gas burning variety. The cylinder of this engine is indicated by the numeral 3 and is provided with th customary reciprocating piston 4. The top of this cylinder 3 is closed by a cylinder head 5 which affords, in the upper end portion of ,the cylinder 3, a combustion chamber 6. The cylinder side and end walls, which latter are formed by the cylinder head, are surrounded by connected water Jackets 1 through which is circulated a cooling fluid or liquid 1/ for the purpose of cooling the engine's cylinder walls to a pre-determined temperature.

The main body of this pump, which body forms the intermediate portion of the pump casing, is indicated as an entirety by 8, the cooperating dome-like upper shell or casing section by 9, and a removable bottom shell or casing section by ID. The dome-like upper shell or casing section 9 is illustrated as being of glass or other transparent material permitting inspection of the pump mechanism under operating conditions. The open lower end of this dome-like transparent upper section is seated on the intermediate pump body-forming section 8 through the medium of a suitable gasket 9a against which gasket said section 8 is normally tightly pressed to form a liquid-tight joint by'means of a suitable clamping device permitting easy removal of the domelike upper section 9 for the purpose of repairs and adjustment. Interposed between the intermediate section 8 and the lower bottom-forming shell or casing section II] is a resilient reciprocable piston-acting diaphragm ll that divides the lower interior portion of the shell-like pump casing into a motivating pressure chamber I2 below the diaphragm ,I I, and a liquid containing pump chamber I3 above said diaphragm l I. The casing section I0 is removably anchored to the and which port I1 is provided with a spring-loadsection 8 and the diaphragm clamped betweenthe sections 8 and In by means of suitable nutequipped bolts H. The diaphragm ii is preferably formed of synthetic rubber or synthetic rubber-treated material, such as is now in common use in diaphragm type fuel pumps.

The body-forming intermediate section 8 is formed to afford a partition wall 8a that extends completely across the interior of the pump housing and forms the top of the pump chamber l3, and said intermediate section 8 is further formed to provide a primary fuel intake passage 8b that opens upwardly into the interior of the domeshaped upper section 9. Still further, the intermediate'body-forming section 8 is formed to afford a secondary fuel inlet passage 80, a fuel pressure chamber 8d, and a final fuel outlet passage 8e. The secondary fuel inlet passage 80 opens downwardly into the pumping chamber 13 through a downwardly opening check-valveed relief valve l8. The downwardly opening check-valve for port 15 is indicated as an entirety by l9 and the upwardly opening checkvalve for the outlet port It is indicated as an entirety by 20. The valves I8, I! and 29 are of identical construction, and each comprise a valve casing 2|, an annular valve seat 22, and a discvalve element 23 that is spring-pressed in the direction of the annular valve seats 22 in a direction opposite to the direction of fluid fiow by a coiled compression spring 24. Preferably a fine screen 25' is provided intermediate the primary and secondary fuel inlet passages 8b and So. In the preferred arrangement illustrated the central portion of the diaphragm II is made rigid by means of opposed reinforcing plates 28 and 21 that are tightly clamped together by means of an axial rivet or the like 28, and the diaphragm is yieldingly biased in a downwardly direction by a coiled compression spring 29'. The primary fuel inlet passage 8b is shown as being in open communication with a fuel delivery conduit 25 that may be assumed to lead from asuitable fuel supply tank or reservoir, such as the gasoline tank of an automotive vehicle, and the final fuel outlet port Be is shown as being in open communication with a fuel delivery conduit that may be assumed to lead to the fuel distributing device or carburetor of the internal combustion engine 2. The motivating pressure chamber l2 of the pump is shown as being in open communication with a pressure conduit 28 that extends thereto from the combustion chamber-forming portion of the cylinder 3 of the internal combustion engine 2. The conduit 28 is connected to the interior of chamber I2 through the medium of an elbow-like coupling 29 that is screw-threaded into the bottom of the lower section III of the pump, and this coupling 29 has an axial bore extending through its bottom which is normally closed, or largely closed, by a plug 38 having a small diameter release passage 3|. The plug 30 forms a condensation sump in the bottom of the fitting 29 below the point of opening of conduit 28 thereinto. The primary end portion of the conduit 28 is formed by the tubular body of the pressure regulating valve previously referred to and which body isindicated as an entirety by 32. This tubular valve body 32 has its lower end screwthreaded into the cylinder head-5 and communicates with the interior of the engine cylinder 3 through a valve cavity 33 and a somewhat constricted primary passage or port 34 in th cylinder head.

The tubular valve body 32 is provided at its lower end with a valve seat 35 and at its upper end, said tubular body, is formed-wlth a similar seat which does not, however, act as a valve seat. Axially slidably mounted within the tubular valve body 32 is a valve stem 36 that is formed at its lower end with a conical valve head 31, and at its upper end with a conical head 38 that is sim- The valve stem 36 is of such length that the valve head 31 will be spaced downwardly. from its cooperating valve seat 35 when the head 38 When the engine is in an inoperative condition, the parts of the valve and pump will all be in the position indicated in the drawing. When the engine is set in operation, the mechanism will function as follows:

During the upward fuel compression strokes or movements of the engine piston 4, a positive pressure (meaning a pressure above atmospheric pressure) will be progressively built up in the engine cylinder and combustion chamber, and so long as the valve 36 remains in its open position, shown in the drawing, the fluid pressure motivating chamber E2 of the pump will be in open communication with the engine cylinder. This increased pressure in the motivating chamber 52 of the pump will cause the resilient pump diaphragm H to move upwardly against the action of the spring 29. Preferably the area of the diaphragm H and the pressure exerted by the spring 25' will be such that the diaphragm will be moved to its upper position under the influence of a relatively very low pressure, such as might be present in the combustion chamber of v the engine during theinitial portion of the fuel compression strokes or movements of the piston.

After the diaphragm H has been moved to its upper position and during the fuel compression strokes or movements of the engine piston. and well before combustion takes place, the floating valve will respond to the rapidly increasing pressure in the engine cylinder, which latter will rise much more rapidly than will the pressure in the motivating chamber l2 due to the restriction offered by the connecting conduit and valve, by moving to its upper position wherein the valve head 31 will cooperate with the seat 35 to close' the conduit to passage of fluid. This disrupted condition of communication between the engine cylinder and pump motivating pressure chamber l2 will be maintained during the balance of the compression stroke, throughthe combustion or firing period,-

and throughout the entire power delivery strokes or movements of the piston a and during the succeeding exhaust stroke or movement of the engine piston. During these succeeding strokes or movements of the piston, during which the valve '37 is closed, the pressure in the motivating chamber I 2 will recede due to outward leakage through the highly restricted vent port 3!, but will not ordinarily recede sufficiently to permit more than of, the valve 31' will return under the action of ravity to its open position, so that during the balance of the intake movement of the pistonthe motivating chamber l2 and diaphragm II will be subject to this reduced sub-atmospheric Pressure, whereupon the diaphragm II will return to its lower position under the combined influence of the spring 29' and suction produced in the engine cylinder. of 001.1158, during each succeeding complete cycle of operation of the engine, the operation just described will be re-- peated so that the diaphragm II will be alternately moved upwardly and downwardly in rapid succession.

With the pump structure illustrated, eachnpward movement of the diaphragm will cause fluid in the pump chamber l8 to be expelled upwardly and outwardly therefrom through the upwardly opening check valve 20 into the pressure chamber 8b,.from which the fluid will be largely expelled through the'passage 8e and the outlet pip 40 to the point of delivery which may be assumed to be the carburetor or other fuel distributing mechanism of the associated internal combustion engine, and each downward movement of the diaphragm II will cause fluid to be drawn into the pump chamber 13 through the downwardly opening check valve is from a suitable source of fuel supply through the intake pipe 25 and primary and secondary fuel intake passages 8b and 8c. The relief valve I8 will remain closed except when pressure in the outlet pipe 40 is built up beyond a predetermined point, at which times the relief valve IE will open to permit circulation of the fluid within the pump casing and thereby relieve the pumping mechanism of excessive loads.

cylinder source of pressure and within the confines of the cooled wall of the head of the engine cylinder, and since the valveis closed at this point during intervals of high temperature and pressure resulting from combustion, gases at excessively high temperatures and pressures will not be permitted to enter any part of the conduit outwardly of the cooled wall of the engine cylinder and, of course, the valve elements themselves will be cooled substantially to cylinder wall temperature. With this arrangement, the actual temperature of cylinder gases injected into the pressure conduit 29 to move the diaphragm upwardly is so relativelylow and the rate of conductivity through the conduit 28 itself from the engine will be so relatively low that no serious rise in temperature of the pumping mechanism or the fluid contained therein, or the fuel conduits leading thereto and therefrom, will be effected even during prolonged periods of operation. In fact, it is important to note that the-temperatures present in the motivating chamber l2 of the pump the treated fabric diaphragm I l The restricted pressure relief port 3| in the conaffords an outlet for condensation that may, at

, times, collect in the conduit 28; and, secondly,

because it permits partial equalization of pressure inthe pressure chamber 12 with respect to atmosphere during periods after the diaphragm has moved to either of its extreme positions, thereby permitting more rapid reversal of the diaphraigm movements under high speed engine operat on.

The pumping mechanism and pressure valve mechanism are herein shown substantially in full 4 t scale but, since the proportions oidiameter to weight in the pressure cut-oil valve mechanism is rather critical, a specific specification or a particular valve that has been found to work well with a number or recent automotive en ines, including several Chrysler built automotive engines of recent manufacture, will herein be set iorth Just as an aid to those desiring to utilize the invention, but without any attempt to limit the invention. As is well known, the engines referred to are of the common four-cycle gas burning variety employing relatively low cylindercomprest sion pressures, as compared to Diesel engines or other oil burning high pressure injection type engines, and using electric spark ignition. In the experiments I have made, very successful results have been obtained with the pressure regulating valve proportioned substantially as follows? Diameter of stem 36 ..inch.- .125 Diameter of bore or orifice in valve body v do .200 Diameter of valve head do .250 Total weight of valve stem unit-- grams 3 The over-all weight of the valve stem with relation to the diameters above given is particularly important since gravity is relied upon to In this respect attention is directed to the fact that the minimum pressure or highest partial vacuum built up in the engine cylinder during intake strokes varies widely under different engine operating conditions, the partial vacuum in the cylinder during suction strokes being reatest during periods of deceleration and being lowest under periods 01 acceleration. Hence, it will be seen that it the valve 31 is closed immediately after the pressure chamber I! has been subject to a maximum degree of partial vacuum obtained in the engine cylinder during a suction stroke under conditions of deceleration and the engine is in a condition of acceleration when the next intake or suction stroke takes place, the valve must either become vacuum bound in a closed position and tail to open, at least during that suction stroke, or must have sumcient weight to open against a considerably greater pressure in the engine cylinder than in the pressure chamber I2 01 the pump. Using the above specifications as a basis for experimentation, very little diillculty should be encountered, in adapting the invention to almost any internal combustion engine.

Since the pressure cut-oil valve is closed during flringstrokes oi the engine and is only open when the gases in the combustion chamber are relatively fresh and clean, there will be very little tendency to clog the pressure conduit with foreign substances or products of combustion, but as a safeguard against clogging of the passage through the valve, which represents the maximum restriction in the conduit, I permit the stem 36 to wobble throughout its length withinthe bore of the valve body and thereby keep itself wiped clean and free of any foreign substances that may tend to further restrict the passage. What I claim is:

1. In a pumping mechanism operated by fluid pressure built up in the piston-equipped cylinder of a gas burning internal combustion engine, said pumping mechanism having a conduit extending to the engine cylinder, and a normally open pressure closed valve controlling the flow through said conduit, said valve comprising a reciprocating valve element and a cooperating valve seat, said reciprocating valve element being yleldingly biased toward open position and being balanced to close under relatively low pressures built up in the engine cylinder during the compression strokes oithe engine piston materially in advance of combustion.

2. In a pumping mechanism operated by fluid pressure built up in the piston-equipped cylinder of a gas burning internal combustion engine having a cooled cylinder wall, said pumping mecha nism having a conduit extending to the engine cylinder through said cooled wall thereof. and a normally open pressure closedvalve controlling the flow through said conduit. said valve comprising a reciprocating valve'element and a cooperating valve seat, said valve seat being located wholly within the confines of the cooled cylinder wall and being in direct heat exchange relationship therewith, said reciprocating valve element being yleldingly biased toward open position and being balanced to close under relatively low pressures built up in the engine cylinder during the compression strokes of the engine piston materially in advance of combustion.

WIIJ'RED W. LOW'I'HER. 

